Pulper rotor and assembly

ABSTRACT

An improved pulper, mixer or defibering, rotor having a spar ring attached to a hub of the rotor with a series of curved vanes projecting from the spar ring. The curved vanes have a vane face and a trailing edge. The trailing edge may be unitary and integral with the vane, or may be segmented in combination with trailing edge portion provided on an underlying spar stub to which the vanes are attached. The hydrodynamic suction created by the trailing edge is enhanced by the addition of a dam at the vane tip end of the trailing edge zone. The vanes have a constant vane face angle relative to radians extending outward from the hub of the rotor. As a result of the constant vane face angle the pulp, or other materials, mixed by the vanes during rotation of the rotor are more consistently in contact with the vanes during rotation of the rotor. The vanes are also streamlined to reduce hydrodynamic drag especially at the vane tips where speed and therefore drag potential are at their highest levels. As a result, increased circulation and pumping effects with minimal power requirements are achieved. The vanes may be made of high wear resistant materials and are easily accessible for maintenance, repair or replacement.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of U.S. Provisional PatentApplication 60/440,532 filed Jan. 16, 2003.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to an improved pulper or mixer rotor withincreased pumping and defibering capacities, reduced power requirements,easier maintenance and interchangeability of parts, and improved wearresistance.

2. Description of Related Art

FIG. 1 shows a conventional pulping, mixing, or defibering apparatus,which generally includes a vat, or tub, 10 formed of side wall 11 andbottom wall 12. In the center of the bottom wall 12 is a perforatedbed-plate 13. The bed-plate 13 permits draining of pulped paper stock,for example, after a pulping operation is completed. A rotor 15 forcirculating the paper stock, for example, or other material, is mountedon a hub 14 in the center of the bed-plate 13. Supports 19 stabilize thepulping tub, or vat, 10.

The rotor 15 creates a mechanical shear and/or hydraulic shear effect onthe pulp, or other material, being mixed. Mechanical shear, for example,is achieved by rotating the rotor 15 above the stationary bed-plate 13so that the paper pulp stock, or other material, is agitated, and thefibers and liquids are approximately separated by being strained throughthe bed-plate 13 under the pressure applied by vanes 17 of the rotor 15.Hydraulic shear, on the other hand, occurs by contacting the paper pulpfibers, for example, with other paper pulp fibers in the tub, or vat, 10as a result of the turbulence, or flow pattern, generated by rotation ofthe rotor 15. The rotor 15 is driven by gears that engage the hub 14. Amotor 22 powers the gears that are housed within gear housing 20.

FIG. 2 shows a conventional pulper rotor 15 with a series of straightvanes 17 extending beyond the outer circumference of a spar ring 16. Thestraight vanes 17 tend to be fairly blunt and thick at a leading vaneface 17 a, and tapers thinner at a trailing edge 17 b of each vane 17.One end of each vane 17 nearest the spar ring 16 joins an outer portionof the spar ring 16. The portions where each vane 17 joins the spar ring16 gradually tapers to form a gulley 17 c. These gulleys 17 c aresusceptible to cavitation wear from the turbulent flow of pulp, or othermaterials passing over the vanes 17 in the wake of the agitationgenerated by rotation of the rotor 15.

FIG. 3 shows that straight vanes 17 result in an angle of the leadingedge of the vane face 17 a varying relative to a radian r_(n), forexample, projecting from the rotor hub 14 to the edge of the vane face17 a. As seen in FIG. 3, for example, the angle of the vane face 17 a ata location nearest the spar ring 16 is 43 degrees relative to a radianr₁ projecting from the rotor hub 14 to a first edge location of the vaneface 17 a, whereas the angle of the same vane face 17 a at an edgelocation furthest from the spar ring 16 is 30 degrees relative to aradian r2 similarly projecting from the rotor hub 14 to the edge of thevane face 17 a. As a result of the change in angle of the vane face 17a, the vane face 17 a strikes the pulp material, or other material beingmixed, less consistently and with less mixing or agitation effectbecause the relative angle of the vane face 17 a lessens as the vane 17extends further from the spar ring 16. That is to say, the pulpmaterial, or other material being mixed by the vane 17 by striking thevane face 17 a, is less likely to be mixed with the same consistency orforce by the straight vane 17 as the rotation of the rotor 15 occursbecause the lessening relative angle of the vane face 17 a encouragesthe materials being mixed to simply slide along the vane face 17 a ofeach vane 17 and outward from the rotary path of the vanes 17. Thus, thepulp, or other material being mixed, in conventional straight vane rotorsystems tend to be ineffectively directed out of contact with the vanefaces 17 a and out of the rotary path of vanes 17, resulting in a moretime-consuming mixing of the materials being required in order toachieve a desired defibering, for example, effect. The additional mixingtime due to the inefficiencies of straight vane rotors requiresadditional power consumption to operate the rotor until the desireddefibering effect on the materials is achieved.

Further, the bluntness of the leading edge of straight vane face 17 asubjects the vane faces 17 a to considerable wear as mixing of materialsoccurs. To compensate for the wear induced by the agitation of materialson the leading edge of straight vane faces 17 a, prefabricated wearplates are often separately welded onto the leading edge of the vanes17. Such straight vane face pulper rotors 15 with welded wear plates maybe relatively easy to make, however, they tend to have some of the sameinefficiencies at pumping materials in desired directions or capacitiesdue, at least partially, to the changing relative angle of contact ofeach vane face 17 a with the pulp, or materials, being mixed asdiscussed above. Further, the requirement of welding wear plates ontothe vanes 17 limits the materials that can be used to those compatiblewith the underlying material chosen for the vane. Such compatibilityrequirements may limit the choice of vane materials to those that aregenerally not the most wear-resistant type materials in order for thewear plates to be successfully welded onto the vanes. Still further,because of the welding aspect of the wear plate, it is often required tochange the entire vane, at least, even when only the wear plate is allthat is worn.

Moreover, straight vane face rotors can be difficult and economicallyinefficient to repair, replace or maintain. For example, often removalof the entire rotor is required in order to replace, repair or servicejust a vane or just a wear plate. The removal of an entire rotor mayrequire additional personnel, and may result in significant inoperabletime of the pulper, or mixer, in general.

To address the inefficiencies of straight vane face rotors, boostervanes 18, as shown in FIG. 2, are frequently used. Such booster vanes 18are also typically welded to the top of the straight vanes 17 to add anadditional material contacting face and to increase pumpingefficiencies. The use of booster vanes 18 still does not render straightvane face rotors optimally efficient however, as the additionalmaterials and production costs render such straight vane rotors 15 withbooster vanes 18 more costly to manufacture. Further, even with boostervanes 18, some materials are already directed away from the vanes 17, ingeneral, by the material's initial impact with the straight vane face 17a as discussed above. Such booster vanes 18 also require increased powerrequirements to achieve increased pumping capacities. Thus, any pumpingefficiency added by the booster vanes 18 may well be offset by the addedmanufacturing and added operational costs incurred with straight vanerotors having booster vanes 18. Further, the introduction of yet anotheradditional part, represented by the booster vane 18, increases the costsand time required for maintenance, repair and/or replacement, whilestill experiencing the inconvenience of having to remove the entirerotor 15 to perform such repair, replacement or maintenance functions.Further still, such booster vanes 18 result in the gulleys 17 c beingparticularly susceptible to cavitation wear as a result of the increasedturbulence of materials flowing in the wake of the booster vane 18induced agitation of the pulp stock, or other material, being mixed.

As with the inefficiencies experienced by the changing angle of the vaneface relative to the series of radians r_(n) projecting from the rotorhub 14, straight vanes 17 also have a varying intersection anglerelative to the underlying bedplate 13 of the conventional pulper rotor15. The interface of the pulp stock, or other material, agitated by thevanes 17 of the rotor 15 and pressed downward toward the bedplate 13results in the desired defibering, for example, of the pulp, or othermaterials, as the liquefied matter passes, as if strained, throughapertures 13 a of the bedplate 13 (see FIG. 4). Thus, because theintersection angle of the vanes 17, relative to the bedplate 13, changesas the vanes 17 extend across the bedplate 13, the pressure imposed uponthe pulp stock, or other material, from the vanes 17 is not consistentlyapplied to the materials from the inner diameter to the outer diameterof the bedplate 13. As a result, defibering efficiency is less thanoptimal.

The inefficiencies of such straight vane rotors with respect to pumpingand defibering inefficiencies, even with booster vanes, and thesusceptibility of straight vane rotors to high wear zones andmaintenance, repair or replacement inconveniences, pose problems theimproved pulper, or mixer rotor, as set forth herein, is designed tohelp overcome. Further the power consumption inefficiencies of straightvane rotors may be minimized by the improved pulper, or mixer rotordescribed herein which helps eliminate the need for such booster vanes,and performs similar mixing of materials in less time, while requiringless power.

SUMMARY OF THE INVENTION

This invention provides an improved pulper, mixer or defibering, rotorhaving a spar ring attached to a hub of the rotor with a series ofcurved vanes projecting from the spar ring. The curved vanes have aconstant vane face angle relative to radians immediately adjacent oneanother and extending outward from the hub of the rotor. As a result ofthe constant relative vane face angle, the pulp, or materials, mixed bythe vanes of the rotor are more consistently in contact with the vanesduring rotation of the rotor. Thus, booster vanes are not required. As aresult, increased circulation and pumping effects with minimal powerrequirements are achieved.

This invention separately provides a series of curved vanes having vanefaces with substantially similar, or preferably equal, surface volumes.As a result of the substantially similar, or preferably equal, vane facesurface volumes, the paper pulp stock, or other materials, being mixedby the vanes in the pulper tub, or vat, remains in contact with the vaneface of each vane for a prolonged period as circulation occurs.

This invention separately provides the series of curved vanes projectingfrom the spar ring as separately attachable to the spar ring via sparstubs. The spar stubs are made of a high strength material integral withthe spar ring, whereas the separably attachable vanes are made with ahighly wear-resistant material. As a result of the separably attachablenature of the vanes to the spar stubs, maintenance is easier as thevanes may be repaired or replaced without requiring removal of theentire rotor. Further because the vanes are separably attached, ratherthan welded, a greater variety of highly wear-resistant materials areavailable to form the vanes. As a result of the high strength spar ringand spar stubs, the need for additionally welded wear plates and/orbooster vanes are not required, thus minimizing weight and powerconsumption. As a result of the highly wear-resistant material, thecirculation and pumping effectiveness of the vanes and rotor continuelonger, reducing the need for repair or replacement. As a further resultof the separably attachable vanes, the opportunity to changeconfigurations of the vanes to meet changing customer needs is also morereadily available.

This invention separately provides vanes having an endplate feature thatimprove the tip suction pulse effect, which recirculates the paper pulpstock, or other material, more easily in the pulper tub, or vat, untilthe desired defibering, for example, is achieved.

These and other features and advantages of this invention area describedin, or are apparent from, the following detailed description of variousexemplary embodiments of the systems and methods according to thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments of the systems and methods of thisinvention will be described in detail with reference to the followingfigures, wherein:

FIG. 1 illustrates a conventional pulper;

FIG. 2 illustrates a conventional straight vane faced rotor with boostervanes;

FIG. 3 illustrates a vane face angle of a conventional straight vanefaced rotor relative to a radian originating from a rotor hub;

FIG. 4 illustrates an improved rotor mounted above a perforatedbed-plate according to at least one exemplary embodiment of theinvention;

FIG. 5 illustrates a bottom view of an exemplary embodiment of animproved rotor according to the invention;

FIG. 6 illustrates another embodiment showing a different mounting ofthe vane to a spar ring;

FIG. 7 illustrates an exemplary embodiment of a single vane according tothe invention;

FIG. 8 illustrates a vane face angle of the improved rotor referred toin FIG. 4 relative to a radian originating from the rotor hub;

FIG. 9 illustrates another exemplary embodiment of a spar stub and vaneaccording to the invention;

FIG. 10 is a schematic view of a composite vane in accordance withanother embodiment of the invention; and

FIG. 11 is a schematic view of another vane structure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The conventional pulper tub, or vat, 10 shown in FIG. 1 shows generallythe type of pulper tub, or vat, 10 with which the various exemplaryembodiments of the improved pulper, mixing or defibering, rotor 35 ofthe invention described herein is intended to be used. Accordingly, likenumerals are used, where possible, in describing the various exemplaryembodiments of the invention when referring to features translatablewith those of the conventional pulper of FIG. 1.

FIG. 4 shows one exemplary embodiment of the improved pulper, mixer ordefibering, rotor 35 of the invention. The pulper, mixer or defibering,rotor 35 includes a spar ring 36 that supports a plurality of vanes 37.The vanes 37 extend generally radially outwardly from the spar ring 36towards an outer circumference of the perforated bed-plate 13. The sparring 36 is mounted about a hub 14 at the center of the bed-plate 13. Thepulper, mixer or defibering, rotor 35 may be driven by a conventionalgearing and motor 22 combination, as generally depicted in FIG. 1.Rotation of the vanes 37 of the pulper, mixer or defibering, rotorcauses paper pulp stock, for example, or other material, to circulate inthe tub, or vat, 10. The circulation of the stock, or other materials,helps achieve the hydraulic shearing effect among the circulating stock,or other materials, as well as the mechanical shearing effect on thestock, or other materials, via the interaction of the rotating vanes 37against the stationary bed-plate 13 at a bottom of the pulper tub, orvat, 10. Once the fibers of the paper pulp stock, or other material, aresufficiently broken down, or defibered, for example, the materials passthrough apertures 13 a of the bed-plate 13.

FIG. 5 illustrates the underside of an exemplary embodiment of thepulper, mixer or defibering, rotor 35. The vanes 37 are demountablyattachable to spar stubs 38 extending from the spar ring 36. The sparstubs 38 may be made integrally with the spar ring 36 as shown in FIG.5. Alternatively, the spar stubs 38 may be separably attached, forexample welded, to the spar ring 36 as shown in FIG. 4. In any event,the spar stubs 38 project, at designated intervals, from an outercircumference of the spar ring 36. The spar stubs 38 may be made of thesame material as the spar ring 36, or of a different material, in orderto provide similar strength and a high degree stability between the sparstubs 38 and spar ring 36.

The spar stubs 38, of the exemplary embodiment shown in FIG. 5, includeattachment devices 39 for securing the vanes 37 to the spar stubs 38.The attachment devices may be any of screws, rivets, projections, orother such structures for securing the vanes 37 to the spar stubs 38. Itis noted that those skilled in the art may fashion other couplingarrangements besides the projection/spar stubs 38 that may be receivedin female grooves or the like shown. For example, the vanes 37 could bedesigned to have male projections on their i.d. ends adapted for receiptin female concavities provided in appropriate locations on the spar ring36. One such alternative coupling design is shown in FIG. 6. Here,specifically configured female slots 100 are provided around theperiphery of spar ring 36. Mating male ends 102 of the vanes 37 aresnugly fitted in the slots and the joint can be further secured by boltsor the like (not shown) that would be inserted through registered bores104, 106 placed respectively in the female and male parts, andcorresponding apertures 108 of the clamp ring 110. A rotor cap 112 isattached over the assembly to secure to the clamp ring.

FIG. 7 illustrates an exemplary embodiment of a vane 37. The vane 37 isseparably attachable to the spar stubs by attachment devices 40corresponding to the attachment devices of the spar stubs. Each vane 37includes a vane face 37 a on the leading edge, a trailing edge 37 b anda spar stub mounting surface 37 c. The vane face 37 a is provided with adesignated vane height h1. The vane height h1 at the vane face 37 atapers to a vane height h2 at the trailing edge 37 b of the vane 37. Thepitch angle of the vane face 37 a is preferably constant, for example at30°, to provide a desired pressure to the paper pulp stock, or othermaterials, being mixed by contact with the vane face 37 a of the vane 37upon rotation. The vane 37 may be slid onto the spar stub 38 (see FIG.5) in order to align the spar stub mounting surface 37 c of the vane 37so that the corresponding attachment devices are aligned to secure thevane 37 to the spar stub 38, and the innermost vane surface 37 d abutsthe spar ring 36 (FIG. 4). The outermost vane surface 37 e of the vane37 is generally curved from the vane face 37 a to the trailing edge 37b. The interface of the trailing edge 37 b and outermost vane surface 37e of the vane 37 provides a lifting effect that sucks fiber off from thestock, or other materials, being mixed by rotation of the rotor 35. Notealso in FIG. 7 that the trailing edge of the vane comprises a curvededge 116 radiused downwardly toward the bed-plate surface. This toohelps to provide a suction pulse that cleans the bed-plate. Furtherprotruding end dam member 114 is provided along the o.d. extremity ofthe trailing edge. The end dam doesn't allow flow to “leak” off the endof the rotor; thereby improving suction and bed-plate cleaning acrossthe entire swept area.

FIG. 8 shows generally, according to the various exemplary embodimentsof the invention, a configuration of the vanes 37 mounted to the sparring 36 by attachment devices 40. The vanes 37 are mounted such that theangle between the vane face 37 a and a radian r₁ extending from thecenter of the hub 14 towards the outermost circumference of the sparring 36 is substantially the same as the angle between the vane face 37a and any other radian, for example r₂, similarly extending from thecenter of the hub 14 and toward the outermost circumference of the sparring 36 or the outermost vane surface 37 e. By substantially the same wemean that the difference in vane face surface to intersecting radianangle for any two points along the vane face surface should not exceedgreater than about 10°. By controlling the angle of the vane face 37 arelative to the spar ring 36, more constant contact of the paper pulpstock, or other materials, being mixed is achieved upon rotation of therotor 35 and vanes 37. Further, because the vanes 37 may be separablyattached to the spar ring 36 by mounting to the spar stubs 38 (FIG. 5),the vanes 37 may be made of a greater variety of materials, such asceramics, urethanes, or other highly wear resistant and durablematerials that previous straight vane faced rotors, for example, werenot able to be made of.

Of course, it should be appreciated that the angles of each of the vanefaces 37 a are not limited to uniformity, rather, the angle of the vaneface 37 a of each vane may be varied to accomplish the desired contactwith the stock, or other materials, being mixed. Likewise, the contouror shape of the vanes 37 may be varied even though mounted on the samespar ring 36, such that one vane 37 may be smooth, and another vane 37may be toothed, for example, or otherwise not smooth, in order toachieve different pulping, mixing or defibering, actions. Similarly,vanes 37 of different lengths may be mounted on the same spar ring 36 toachieve different pulping, mixing or defibering, actions as well.

Certain advantages of the various exemplary embodiments of the rotor 35using the separably mounted vanes 37 of the invention versus standard,or conventional, rotors may occur. For example, the various exemplaryembodiments of the rotor 35 and vanes 37 will achieve the same thrust(Th) using significantly less horsepower (hp) than standard, orconventional, rotors. As a result, not only will more stock, or othermaterials, be in contact with the vane face 37 a of the vanes 37, asdescribed with reference to FIG. 7, for example, but the efficiency ofthe pulping, mixing or defibering will be increased as well while lesspower will be used as evidenced by higher thrust/horsepower ratios(Th/hp) than conventional designs. Additionally, a greater volume, orquantity, of stock, or other materials, may be pulped, mixed ordefibered per unit time (sec) as would be evidenced by the quantity totime ratio (Q).

Thus, not only are the various exemplary embodiments of the separablyattached vanes more efficient, they also are more durable and wearresistant due to the choice of materials available to comprise each vane37. Moreover, even were replacement or repair of the vanes 37 required,such replacement or repair is relatively easy as the rotor 35 may beleft in the pulper tub, or vat, 10, for example, whereas prior artconventional rotors require the complete removal of the rotor in orderto work only on the vanes, or other vane related components, forexample.

FIG. 9 illustrates another exemplary embodiment of the vanes 47according to the invention. The vanes 47, according to the exemplaryembodiment shown in FIG. 10 differ from the vanes 37 shown in FIG. 7,which illustrate vanes 37 having a continuous trailing edge 37 bextending from the innermost vane surface 37 d to the outermost vanesurface 37 e and integral with each vane 37. As a result, the vanes 37are mounted by sliding over the spar stubs 38, in a generallyperpendicular direction relative to the spar ring 36, towards the sparring 36. The exemplary embodiment of the vanes 47 shown in FIG. 9, onthe other hand, provides spar stubs 48 joined at one end to the sparring 36 and having an outer end 48 a opposite the spar ring 36. Eachspar stub includes a first trailing edge portion 48 b extending from thespar ring 36 to an outer end 48 a of the spar stub 48.

A vane 47 having a vane face 47 a and a second trailing edge portion 47b is slidingly mounted over each spar stub 48, in a generally lateraldirection relative to the spar ring 36, such that the first trailingedge portion 48 b of the spar stub 48, and the second trailing edgeportion 47 b of the vane 47, are immediately adjacent one another toform the equivalent of the unified trailing edge 37 b of the exemplaryembodiment described with reference to FIG. 7 above. Once alignedappropriately over the spar stub 48, the vane 47 is attached to the sparstub 48 in a manner as described with reference to the exemplaryembodiments discussed above.

The vanes 47 of the exemplary embodiment illustrated in FIG. 9 have vanefaces 47 a of a constant pitch angle such that the stock, or othermaterials, being mixed are more readily contacted by the vane face 47 aas the rotor 35 and vanes 47 rotate. Likewise, the vane 47 tapers from aheight h1 at the vane face 47 a to a height h2 at the combined trailingedge formed of first trailing edge portion 48 b and second trailing edgeportion 47 b.

The vanes 47 thus provide similar advantages to those described withreference to the exemplary embodiments discussed above. Such advantagesinclude the greater choice of materials to form the vanes 47, moreflexibility in the arrangement of vanes 47 on the spar ring 36, greatercontact area and contact time of the materials being mixed with the vaneface 47 a, decreased power requirements, and easier accessibility formaintenance and repair of the vanes 47.

An alternative vane structure is shown in FIG. 10. Here, the face 37 aof the vane comprises a wear plate 118 made of a hard metal that is, forexample, investment cast to the desired shape. The trailing body section214 of the vane may be formed from a filler/bonding material. As shown,spar stub 38 is partially in phantom and includes a male mounting end116 adapted for reception in a female recess or the like in the sparring (not shown). The body section 214 may hold the face plate and sparstub 38 together and provide the required hydraulic profile. Bodysection 214 may be composed of an urethane/epoxy but could also be abi-metal cast process.

FIG. 11 illustrates another unique aspect of the invention. Here, theid. surface of the vane is shown at 140 with the o.d. surface depictedas 142. One inner length of the vane shown at 150 is shorter than anouter vane length shown at 152. The vane length in this embodimentincreases progressively from inner vane location toward outer vanelocation. In operation, this vane length/section increases as theperipheral shield of the vane location increases to improve performanceand reduce drag.

It is apparent that the vane member shown in FIG. 11 is streamlined toenhance operational performance. The vane member is adapted for radialdisposition on a hub or the like in a pulp and paper apparatus. The vanemember is rotatable around a central axis that extends through the huband the vane has an inner-end adapted for positioning adjacent to thehub at an opposing outer edge at an outer radially directed extremity ofthe vane. The vane comprises a leading edge 190 and a trailing edge 192.The vane lengths are shown at 150 and 152 and they are defined as thedistance between the leading edge and the trailing edge at given pointsalong a continuum 160 that extends in the radial direction from theinner-end of the vane to the outer-end. In accordance with this aspectof the invention, the vane length increases as one proceeds along thecontinuum from the inner-end to the outer-end.

In operation, with any of the exemplary embodiments of the improvedpulper, or mixer, rotor 35 described herein, including the spar ring 36,spar stubs 38 or 48, and vanes 37 or 47, paper pulp stock, or othermaterial, is placed into the pulper tub, or vat, 10. The motor 22 isthen operated to drive the gear 20. The gear 20 engages the hub 14, towhich rotor 35 is mounted. The rotation of the rotor 35 therefore causesthe vanes 37 or 47 to rotate in a direction such that the vane face 37 aor 47 a contacts the stock, or materials, initially. As rotation of therotor 35 and vanes 37 a or 47 a occurs, more consistent contact of thestock, or materials, with the vane face 37 a or 47 a is maintainedresulting in increased agitation and mixing of the materials. Inaddition, the trailing edge 37 b, or the combined first trailing edgeportion 48 b of the spar stub 48 with the second trailing edge portion47 b of the vane, helps lift fibers, for example, from the stock, ormaterials, being mixed such that defibering is achieved. The defiberedmaterials, for example, are then passed through the apertures 13 a (FIG.4) in the bed-plate 13 underlying the rotor 35 at the bottom of the tub,or vat, 10.

In summary, one aspect of the invention is directed toward thecombination of demountable vane members that are adapted to be mountedover and carried by the spar stubs with the spar stubs being fixed tothe annular spar ring by welding or the like. The demountable vanes maybe composed of any one or more of a variety of wear resistant materialssuch as for example, wear resistant initial such as “stellite”, castcobalt alloys, polyurethanes, even ceramic materials.

In another aspect of the invention, each of the leading surfaces of thevanes presents a substantially constant angle relative to at least tworadians that extend from the rotor axis to any two points located alongthat leading cage. By “substantially constant”, we mean that this angleshould not vary by more than about 10°. It is generally desirable thanthis angle, as measured between the axis and to a point or tangent alongthe leading edge should be between about 10° to about 60°, preferablyabout 300 to about 40°. In many cases, it will be advantageous if eachof the vanes (and their corresponding leading edges) possesses this sameleading edge angle.

While the invention has been described with reference to the exemplaryembodiments set forth herein, it should be appreciated that otheralternatives, combinations, modifications and variations are apparent tothose skilled in the art. Accordingly, the preferred embodiments of thisinvention, as set forth above, are intended to be illustrative only, andnot limiting. Various changes can be made without departing from thespirit and scope of this invention.

1. Apparatus for pulping paper pulp comprising a rotor having a centralhub and an annular ring surrounding said hub, vane members extendingradially outwardly from said annular ring and being demountably attachedto said ring.
 2. Apparatus as recited in claim 1 wherein said vanemembers and said ring comprise complementary coupling means fordemountably attaching said vane members to said ring.
 3. Apparatus asrecited in claim 2 wherein said coupling means comprise cooperating maleand female members.
 4. Apparatus for pulping paper pulp comprising arotor having a central hub and an annular spar ring surrounding saidhub, said spar ring carrying a plurality of spar stubs fixedly connectedto said annular spar ring, a plurality of vane members, each said vanemember being demountably attached to one of said spar stubs. 5.Apparatus for pulping a paper pulp suspension, said apparatus comprisinga rotor adapted for rotation around a central axis, said rotor carryinga plurality of vane members, each of said vane members extendinggenerally radially outwardly relative to said axis, each said vanemember comprising a leading edge adapted to lead said vane, uponrotation thereof, through said suspension, said leading edge of at leastone of said vanes having a face surface with a plurality of pointsdisposed along said surface, said face surface exhibiting asubstantially constant angle relative to radians extending from saidaxis to any two of said points.
 6. Apparatus as recited in claim 1wherein said substantially constant angle is within a range of about 10°to about 60°.
 7. Apparatus as recited in claim 6 wherein said constantangle is within a range of about 30°-40°.
 8. Apparatus for pulping apaper pulp suspension, said apparatus comprising a rotor adapted forrotation around a central axis, said rotor carrying a plurality of vanemembers, each of said vane members extending generally radiallyoutwardly relative to said axis, each said vane member having a leadingedge adapted to lead said vane upon rotation thereof, through saidsuspension, said leading edges of each of said vanes having a facesurface with a plurality of points disposed along said face surface,said face surface of each vane exhibiting a substantially constant anglerelative to radians extending from said axis to any two points alongsaid vane.
 9. Apparatus as recited in claim 5 wherein of each said vanesexhibits the same substantially constant angle.
 10. A rotor mounted on ahub, the rotor comprising: a circular spar ring having an outercircumference, the spar ring being mounted on the hub and beingcomprised of a first material; a series of spaced apart spar stubshaving an inner end and an outer end, the inner end of each spar stubadjoining the outer circumference of the spar ring such that the sparstub extends from the outer circumference of the spar ring to the outerend of each respective spar stub, and a first side edge opposite asecond side edge; and a series of vanes separably attachable to acorresponding one of the series of spar stubs, wherein each vane has avane face with a constant vane face angle relative to radians extendingfrom the hub to a respective vane face, and each vane has a trailingedge opposite each vane face.
 11. The rotor of claim 10, wherein thespar stubs are made integral with the spar ring and are comprised of thesame first material as comprises the spar ring.
 12. The rotor of claim10, wherein the spar stubs are separably attachable to the spar ring.13. The rotor of claim 12, wherein the spar stubs are comprised of thesame first material as comprise the spar ring.
 14. The rotor of claim12, wherein the spar stubs are comprised of second materials differentthan the first material comprising the spar ring.
 15. The rotor of claim10, wherein the vanes are slidably attachable to corresponding sparstubs in a direction from the outer end of a respective spar stub to theouter circumference of the spar ring.
 16. The rotor of claim 10, whereineach spar stub further comprises a first trailing edge portion extendingpartially along a respective spar stub from the outer end of therespective spar stub towards, but not to, the outer circumference of thespar ring.
 17. The rotor of claim 16, wherein the outer trailing edgeportion of each vane comprises an end dam.
 18. The rotor of claim 16,wherein the first trailing edge portion is comprised of the samematerial as comprises the respectively corresponding vane and secondtrailing edge portion.
 19. The rotor of claim 17, wherein the vanes areslidably attachable to corresponding spar stubs in a generally lateraldirection relative to the spar ring, from the first side edge of eachrespective spar stub to the second side edge having the first trailingedge portion of each respective spar stub and vane immediately abut oneanother and form a trailing edge.
 20. The rotor of claim 10, wherein thevanes are comprised of hardened metallic materials.
 21. The rotor ofclaim 10, wherein the vanes are comprised of non-metallic materials. 22.A method of separating materials, comprising: providing a tub having anapertured bed-plate, a rotor mounted above the bed-plate, the rotorhaving vanes, each vane having a constant vane face angle relative toradians extending from the hub to a respective vane face, and each vanehaving a trailing edge; supplying materials to be separated into thetub; rotating the vanes; maintaining contact with the materials on eachvane face to separate desired portion of the materials from undesiredportions of the materials; passing the materials over each trailing edgeto generate increased hydraulic suction and separation of the desiredportions of the materials from the undesired portions of the materials;and urging the desired portions of materials out of the tub through theapertured bed-plate.
 23. The method of claim 22, wherein each vane isseparably attachable to said hub.
 24. The method of claim 22, whereineach vane is comprised of wear resistant, metallic materials.
 25. Themethod of claim 22, wherein each vane is comprised of wear resistant,non-metallic materials.
 26. Vane member adapted for rotational movementabout a central axis in a pulping apparatus, said vane member comprisinga leading edge, a trailing edge, and a body between said leading edgeand said trailing edge, said leading edge comprising a face plate, saidface plate composed of a metallic material.
 27. Vane member as recitedin claim 26 wherein said body is composed of an urethane/epoxy material.28. Vane member as recited in claim 26 wherein said body is comprised ofa metallic material different from said face plate metallic material.29. Vane member adapted for radically disposed orientation on a hub in apulp and paper apparatus and being rotatable around a central axisextending through said hub, said vane having an inner end adapted forpositioning adjacent said hub and an opposing outer edge at an outerradically directed extremity of said vane, said vane comprising aleading edge and a trailing edge, a vane length being defined as thedistance between said leading edge and said trailing edge at any givenpoint along a continuum extending from said inner end to said outeredge, said vane length increasing as measured along said continuumproceeding from said inner end to said outer edge.
 30. Vane member asrecited in claim 29 further comprising an end dam positioned on saidtrailing edge adjacent said outer edge.